Can openers have reached a point in development where there have been relatively few improvements added over the basic elements of providing means to engage the underside of the built-up rolled over metal rim of the can container to pass the flat circular surface of the can lid or top through a cutter blade. In can container manufacture, the lid is a flat metal circular surface with a stepped rim at its periphery which forms an annular groove into which the can cylindrical sides are inserted. The stepped rim is then crimped to form the built-up rolled over metal rim. This built-up rolled over metal rim at the top of the can is commonly called the can bead or the bead. In most common tin plated sheet metal can containers, solder is added around the outside periphery of the bead to insure mechanical rigidity and air tightness.
As mentioned above, the usual and most common can openers employ a traction wheel which forcibly engages the underside of the bead while a rotatable cutter wheel is forced into the top of the can immediately interiorly to the top of the bead. With applied mechanical pressure, generally by holding two handles together, one handle havihg attached the traction wheel and the other handle having attached the cutter wheel, the can is rotated under the cutter wheel by rotation of the traction wheel until the can has rotated at least one time and the can top then severed completely around. At that point, the handles of the can opener are separated, disengaging the cutter wheel from the top of the can and permitting removal of the can and the severed top by lifting the can up off the traction wheel.
The above described can openers are similarily functionally described in patents which issued in the early 1950's, such as in the patents to Tuccori, Waller, Tuccori, and Hult, U.S. Pat. Nos. 2,551,183, 2,555,835, 2,632,946, and 2,715,265 respectively.
The above described can opener and referenced patents operate quite satisfactory on the tin plated steel can container which has been available to the public for many years. However, within the recent past, can containers with sides and bottom made from a single piece of extruded aluminum and a top affixed in the usual rolled over manner as was the practice with the tin plated sheet steel cans, except perhaps for soldering the top to the sides of the can, have become quite numerous in the market place. These can containers which the beverage industry is using very extensively usually have a push type or lever operated punch tab in the top for the user to remove the contents. However, there may be instances where the user wishes to remove the top of the can, either before or after the contents of the can have been removed, through the use of the punch tab type opening. This is especially so if the user contemplates a further use for the can not connected with the original beverage bottler, such as for storage of liquids, odd and ends, or perhaps as a reusable drinking container. All these uses are made practical if the tops are removed immediately adjacent to the inside of the can bead so that any sharp edges which might be left by the top removal operation and which might cut the person are not accessible to the person putting the can container to later use.
However, in the construction of the extruded aluminum can containers which are utilized by the beverage bottlers, the top is recessed inwardly a small amount, usually 1/16th. to 1/8th. inch from each side where the top of the can is joined to the sides of the can when the bead if formed. By this recession of the top of the can, the commonly available and conventional can openers do not remove the tops of the beverage cans. Depending upon the particular orientation of the traction wheel and the cutter wheel on the opener, or in some can openers that utilize a stationary cutter blade in place of the cutter wheel, the available can openers can not open the recessed top cans. In some can openers, because of the indentation or recession of the top, it is not possible to place the can bead between the traction wheel and the cutter wheel or cutter blade; and in other can openers, the bead tends to ride up and between the traction wheel and the cutter wheel or cutter blade so that the cutter wheel or cutter blade does not engage the top of the can to begin severing the top. However, it was discovered that if the extruded aluminum recessed top can container were held out an an angle greater than where the conventional can container resides, the can opener would operate, except that there was a tendency to fall away from the position and required that the container be held in that position, and in addition, that the cutter blade would cut through the top of the can and would also cut through the side of the can so that the resultant can container with the top removed presented a sharp edge which gave rise to the possibility of cutting a finger of the user. In these cases, the bead had been completely severed from both the top of the can and the sides also.
Thus it became apparent that if a person wished to remove the top of the new extruded aluminum beverage type can containers, it was necessary to either devise a new can opener or that improvements be added to existing can openers to perform the operation. Further, if the improved can opener were used to open the new type beverage can containers, in order for it to be practical in the market place, the ability of the original can opener to open the usual straight-sided can container should not be removed to add the improvement--that the improved can opener should still open both types of can containers.
Accordingly, it is to these ends that the subject invention is directed, i.e., to present an improvement to conventional can openers which adds to their function the ability of opening the can containers with recessed tops.